arsman, the S2's mic cannot be routed into Traktor so you can't record it on the loop recorder. You can record playing cue points or playing remix decks though.
Just got the Loopy app for iPhone ($3, http://loopyapp.com) Made by the folks who make Audiobus.
No Fx, but the app does looping very well. You can import & export your own loops also, but I haven't gotten that far into it yet. It's a lot of fun, and good for laying down ideas for tunes, as well as beat boxing or loop performance practice.
Dub Fx had a go with it.
I am fairly new to IOS audio, but I just figured out that with Loopy($3), Audiobus(on sale for $5), and Vocalive (on sale for $10) apps, for $18 you can have a kick ass loop station.
I also found a deal on the iRig Mic and iKlip Mini here at a Trusted Google Site if any one is interested, it is shipping from China, but they accept PayPal so no worries.